Genetic analysis of two terpenoid variants in cotton (Gossypium hirsutum L.)

We conducted genetic analysis of two terpenoid aldehyde (TA) variants trans ferred to G. hirsutum L. A high level of methylation (ME) was transferred f rom G, barbadense L. by direct backcrossing to G. hirsutum. Raimondal accum ulation (RA), unique to G. raimondii Ulbr., was transferred by producing a synthetic amphidiploid and backcrossing to G. hirsutum. Progeny tests of th e two TA variants were conducted in the field to ensure that the phenotypic expression was repeatable under field conditions and that plants used in t he genetic analysis were homozygous. The TA variants were crossed on to TM- 1 and the F-1 TA profiles were determined. The F-1 with the ME line had a w ild-type (WT) TA profile that indicated that ME was recessively inherited. The F-1 was self-pollinated to produce an F-2, and the F-1 was crossed with the ME line to produce a backcross (BC). Segregation in both populations c onfirmed that ME was conditioned by a single recessive allele, and we assig ned it the symbol meme. The F-1 with the RA line expressed raimondal that i ndicated that RA was dominantly inherited. The F-1 was self-pollinated to p roduce an F-2, and the F-1 was crossed to TM-1 to produce a BC. Segregation for the RA variant was complex, in the F-2, segregation was 9 raimondal: 7 none, and in the BC segregation was 1 raimondal: 3 none. This segregation conformed to the segregation of alleles at two loci with epistasis in which a variant allele has to be present at both loci before raimondal is produc ed. We assigned the gene symbols Ra,Ra,Ra,Ra, to the RA variant. Linkage te sts were conducted with virescent-l (v(1)), cup leaf (cu), glandless-1 (gl( 1)), frego bract (fg), cluster-1 (cl(1)), Red plant(R-1), Okra leaf (L(2)de grees), Tomentum (T-1), Petal spot(R-2), Yellow pollen (P-1), Yellow petals (Y-1), Brown lint (Lc(1)), and Naked seed (N-1). Neither of the TA variant s showed any linkage with the markers in our tests.